1. Field of the Invention
The invention pertains to an apparatus and method for flipping articles. In particular, the invention relates to an apparatus for flipping selected articles from a stream of such articles so that the articles can be transported to a manufacturing process after having been flipped over approximately 180.degree. from an initial position within the stream. The invention is particularly useful in manufacturing food articles, such as cookie sandwiches, and the like, wherein it is necessary to flip every other cookie in a stream of items released from a baking process so that an automatic cookie process can easily manufacture cookie sandwiches.
2. Description of the Related Art
In the preparation of food articles such as cookies, candies, and the like, after the items have been baked, they are transferred from an oven to an infeed conveyor belt in a stream-like manner so as to be conveyed thereby to a processing station. Where the process is for making cookie sandwiches, a filling station is required to deposit a cookie filling substance, such as cream, onto every other cookie in the stream. It was the prior practice in the baking industry to manually remove an untilled cookie from the conveyor belt and place it on the cookie having the filling substance deposited thereon. Obviously, such practice is rather labor-intensive and time consuming.
U.S. Pat. No. 5,287,953 to Mims, the inventor of the present invention, discloses a successfully automated process of producing cookie sandwiches. The patented system includes an apparatus for receiving, in an infeed section, a stream of distributed articles, such as food items and the like, deposited in rows of like position; that is, each item has a top and bottom surface, and each row is oriented such that the items have the top surface facing upwards from a conveyor belt in the infeed section. The items are allowed to exit the edge of the infeed section towards a transport mechanism, such as an endless loop conveyor belt and the like. A slide mechanism is used to retard the motion of the items as they exit the infeed section.
This device is illustrated in FIG. 4. In particular, the slide mechanism 11' is selectively movable from a slide position to a flip position. In the slide position, a primary sliding surface of the mechanism is positioned directly below the edge of the infeed conveyor belt 10' such that the surface forms an angle with the horizontal plane of the belt. In operation, the item exits the edge of the belt and slides across the primary slide surface and onto a second slide mechanism 12' having a secondary slide surface that is positioned to be in substantially the same plane as the primary slide surface. The item continues to slide along the secondary surface until it comes to rest at a junction formed by the secondary surface and a snubber bar 13' stretching the entire width of the secondary slide surface.
In the flip position (see the phantom line in FIG. 4), the slide mechanism 11' is positioned directly in front of the conveyor belt edge. The slide mechanism has an abutting surface that faces the belt edge when the items are dropped from the conveyor belt. In operation, the slide mechanism is moved into the flip position for every other row of items. The items to be flipped come off the conveyor belt and come into contact with the abutting surface. This surface changes the direction of the item as it moves towards the transport mechanism in conjunction with a reverse slide surface of the second slide mechanism 12'. The item slides down the reverse slide surface on its top surface, thus flipping over approximately 180.degree. from its orientation on the infeed conveyor belt 10'.
The flipped item is then supported above a conveying surface on retractable plate 15. Retractable plate 15' is subsequently retracted to allow the item to fall onto the conveying surface at a predetermined time relative to release of the slid item by snubber bar 13'.
A first row of items is released onto the transport mechanism by the snubber bar and then a second row is flipped and placed on the transport mechanism behind the first row. Therefore, the second row must be flipped quickly and immediately placed on the transport mechanism in order to maintain a desired pitch between items at a high throughput rate.
However, the system described above is limited in rate due to the relative allocation of time for each step because of the interdependence of the various steps. This is especially true for the flipped items which must be placed on the transport mechanism quickly. In being flipped and dropped onto the transport device, and accelerated, the flipped items are often displaced from their proper position. Also, the items are handled while undergoing oscillatory motion, due to the flipping and dropping, and thus handling errors can occur at high speeds. Finally, because position of the flipped items on the transport device is affected by the action of the retractable plate, the bounce of the item, and the friction of the transport device, positioning errors occur.
The limitations of the known device discussed above are best understood through FIG. 5, which is a timing chart for the various elements of such a device. The timing chart of FIG. 4 represents a rate of 200 rows of items per minute on a machine developed by the inventor.
The timing chart of FIG. 5 utilizes time increments of 1/30 of a second for comparison purposes. However, this timing increment can vary based on the application. Notwithstanding any variance in the time increment, the relative time values remain essentially the same because the operation of each element is dependent on the other elements. This will become clear based on the discussion below.
As illustrated in curve (a) of FIG. 5, a row of items is released, i.e., comes to the end of the infeed conveyor every 9 time units. At 1/30 second per time unit, the result is 200 rows of items per minute. Specifically, a top (unflipped) item is released at 0 time units, a bottom (flipped) item is released at 9 time units, and so on. In this example, every other item is flipped and thus the slide mechanism is alternately placed in the slide and flip positions discussed above. Specifically, as a first top item comes off of the infeed conveyor, the slide mechanism is in the slide position, as a second bottom item comes off of the infeed conveyor, the slide mechanism is in the flip position, and so on, as illustrated by curve (b) in FIG. 5.
The first top item is slid along the sliding mechanism and comes to rest against the snubber bar at 6 time units as is illustrated by dotted line x in curve (d) of FIG. 5. This item is held by the snubber bar until 16 time units at which time the snubber bar is raised, i.e., opened, and the item slides onto the conveying device, as illustrated in curve (d). In the meantime, the second bottom item was released at 9 time units, flipped by the slide mechanism and reaches the retractable plate at 14 time units, as illustrated by dotted line y in curve (c) of FIG. 5. At 15 time units, the retractable plate is retracted, as illustrated in curve (c), to allow this item to drop onto the conveying device at a position behind the first item which has been released from the snubber bar as described above. Of course, this process is repeated to deposit alternately flipped and unflipped items on the conveying device with a substantially constant pitch between each item.
It is clear that the operation of the snubber bar and the retractable plate are dependent on one another in order to properly register, i.e. position, the items. Specifically, the snubber bar must remain raised for a predetermined period of time after releasing an item, about 2 time units, in order to allow the item to slide onto the conveying device. Also, the snubber bar must be lowered, i.e., closed, very quickly after this time period to catch the next item. For example, in Applicant's device, the second top cookie reaches the snubber bar at 24 time units (see dotted line x' in curve (d) of FIG. 5) and the snubber bar is completely closed at 23 time units. This leaves little room for error or increases in speed.
Further, in Applicant's device, the bottom item reaches the retractable plate at 14 time units and must be released at 15 time units in order to be properly positioned, i.e., positioned at a constant pitch with respect to the other items, on the conveying device. Therefore, the bottom item is held on the retractable plate for only one time unit, as illustrated in curve (c) of FIG. 5. This does not allow adequate time for oscillatory motion of the item to dissipate.
As is apparent from the discussion above and the curves illustrated in FIG. 5, the operations of the various elements are dependent on one another. Specifically, the retractable plate is used to control the position of the flipped items on the transport device and thus the retractable plate must be retracted immediately after the flipped item is placed thereon in order to allow the flipped item to follow the slid item. Therefore, there is not adequate settling time for allowing oscillatory motion of the flipped item, due to flipping, to dissipate. Also, additional oscillatory motion is generated as the item is dropped onto the transport device when the retractable plate is retracted. This is particularly a problem with items of irregular shape. All of this oscillatory motion, generated by the flipping and dropping of the item, as well as by friction between the transport device and the item, causes positioning errors of the flipped items and thus renders it difficult to effect additional automated handling of the items.